I saw this movie when I was a kid in the early 90s. Im positive its release was no earlier than the late 80s. My memory of the film is vague, but these two sisters.. probably 11 years old.. go ape s**t and start killing. The only scene I remember some what in depth is at the end one sister sends the other running into the ocean while she sprays her from behind with bullets. I emailed Joe Bob Briggs about this one. He had no idea what it was.